1. Field of the Invention
The present invention relates to a waterproof structure in a cable insertion section, that is, a section into which a cable member of the waterproof connector or the like is inserted is waterproofed and to a method of manufacturing the waterproof structure.
The present invention also relates to a waterproof molding die for forming a waterproof mold to be attached to wiring material having lead wires provided therein.
2. Description of the Related Art
In relation to a waterproof connector, an attempt has hitherto been made to block intrusion of liquid into a space defined between an outer peripheral surface of each wire and an inner peripheral surface of a wire insertion hole into which a corresponding wire is to be inserted, by means of attaching a rubber plug to each wire to be assembled (a first related-art example). In another attempt to block intrusion of liquid, there is employed a waterproof structure utilizing a plate-like single-piece rubber plug, wherein a plurality of electric wires to be assembled are fitted into a plurality of previously formed wire conduit sections, thus collectively rendering the electric wires waterproof (a second related-art example). In still another attempt to block intrusion of liquid, there is employed a structure which renders electric wires waterproof by means of filling an electric wire insertion section, into which electric wires are to be inserted, with resin and solidifying the resin (a third related-art example)
For example, FIG. 10 shows structure of a waterproof connector 2 utilizing a single-piece rubber 1. A housing body 3 of the waterproof connector 2 molded from resin has a plurality of terminal attachment sections 3a into which connector terminals 5 connected to conductor terminal sections of electric wires 4, respectively, are to be fitted in an unremovable manner and an electric wire insertion section 3b projectingly formed in a substantially-angular cylindrical shape, situated on one end face side of the terminal attachment sections 3a, and inserted the electric wires 4.
The single-piece rubber 1 is formed from rubber material having a shape of a substantially-rectangular plate and being elastically deformable, the rubber material which is slightly larger than an inner shape of the electric wire insertion section 3b so as to come into closely contact with the inner peripheral surface of the electric wire insertion section 3b when the single-piece rubber 1 is pushed into and fitted to the electric wire insertion section 3b. Wire through holes la are formed in the single-piece rubber plug 1 so as to correspond to the terminal attachment sections 3a, respectively, and each electric wire 4 passes through and is held in a corresponding wire through hole 1a. 
The waterproof connector is further provided with a holder body 6 for pressing the single-piece rubber plug 1 fitted into the electric wire insertion section 3b from an outside thereof. Similarly, the holder body 6 is formed wire insertion holes 6a through which the connector terminals 5 and the electric wires 4 passes so as to correspond to the connector terminals 5 and the electric wires 4. A latch piece 6b is formed so as to extend from each side edge of the holder body 6. A latch projection 3c formed so as to protrude from an outer peripheral side on either side of the electric wire insertion section 3b is removably latched in a latch hole 6c formed in each latch piece 6b, thereby pressing the outer side surface of the single-piece rubber plug 1 and unremovably hold the plug 1.
However, the waterproof structure of the waterproof connector according to the first related-art example adopts a method of attaching each of rubber plugs to each of electric wires. Because of this, attaching a rubber plug to a wire involves consumption of time during an assembly operation. Further, use of the rubber plugs hinders miniaturization of a waterproof connector associated with miniaturization of a connector terminal.
The waterproof structure according to the second related-art example has a merit of contributing to realization of a compact multi-contact waterproof connector. However, when each electric wire 4 is caused to pass through a corresponding wire through hole la of the single-piece rubber plug 1, there is a necessity of first squeezing the connector terminal 5 connected to the electric wire 4. At this time, the connector terminal 5 is squeezed into the wire through hole la while holding the electric wire 4. In association with miniaturization of the connector terminal 5, the diameter of the electric wire 4 has become reduced. It is difficult to pass the connector terminals 5 through wire through holes 1 while holding the electric wires 4 due to buckling of the electric wires 4 and the like.
Further, as a result of an increase in the number of contacts in a connector, a task for assembling a connector by means of inserting the connection terminal 5 and the electric wire 4 into a corresponding wire through hole la formed in the single-piece rubber plug 1 takes a lot of trouble to be the task difficult. Even when the single-piece rubber plug 1 is used, there is a necessity of a countermeasure for sealing unoccupied wire through holes la through use of a dummy plug or film.
The waterproof structure according to the third related-art example obviates a necessity of use of an individual rubber plug to be attached to each electric wire, such as that described in connection with the first related-art example. Further, the waterproof structure according to the third related-art example also obviates a necessity of a task for causing the connector terminal 5 and the electric wire 4 to pass through a corresponding wire through hole la formed in the single-piece rubber plug 1, such as that described in connection with the second related-art example. On the other hand, the waterproof structure, however, involves solidification of the wire insertion section by means of filling it with resin. Because of this, upon discovery of an attachment failure having arisen when the connector terminal is attached to the terminal attachment section or upon the connector terminal sustaining damage, the plug can be neither replaced or subjected to maintenance.
The present invention has been conceived in light of the problems set forth the above and aims at providing a waterproof structure in a cable insertion section in an attempt to improve ease of assembly and maintenance, as well as at providing a method of manufacturing the waterproof structure.
According to a first aspect of the invention, there is provided a waterproof structure in a cable insertion section, wherein an inner peripheral surface of the cable insertion section and an outer peripheral surface of a cable member are sealed together in a cable-inserted state in which connector terminals of cable members connected to ends of individual conductors are inserted into the cable insertion section formed in a housing body and are provided at predetermined positions, the waterproof structure comprising: a plug molded on the outer peripheral surfaces of the cable members situated in the cable insertion section and detachably fitted into the cable insertion section with a slight gap between the inner peripheral surface of the cable insertion section and the plug; and a elastically deformable annular sealing body retained in a retention groove formed along an outer peripheral surface of the plug and brought into close contact with the inner peripheral surface of the cable insertion section.
According to a second aspect of the invention, there is provided the waterproof structure according to the first aspect of the invention, further comprising a holder member having a cable insertion opening smaller than the plug, wherein the holder member having a cable insertion opening smaller than the plug may be detachably engaged with the cable insertion section from an outer surface of the plug while the cable members are inserted into the cable insertion opening.
According to a third aspect of the invention, there is provided a method of manufacturing a waterproof structure in a cable insertion section, wherein an inner peripheral surface of the cable insertion section and an outer peripheral surface of a cable member are sealed together in a cable-inserted state in which connector terminals of cable members connected to ends of individual conductors are inserted into the cable insertion section formed in a housing body and are provided at predetermined positions, the method comprising the steps of: inserting the cable members into a elastically deformable annular sealing body movably to realize the cable-inserted state; detachably fitting a plug into the cable insertion section with a slight gap between the inner peripheral surface of the cable insertion section; molding the plug on the outer peripheral surfaces of the cable members situated in the cable insertion section to form a retention groove for holding the sealing body being in an outer peripheral surface of thereof; and fittingly squeezing the plug into the cable insertion section while the sealing body is retained in the retention groove in the molded plug to bring the sealing body into close contact with the inner peripheral surface of the cable insertion section.
According to a fourth aspect of the invention, there is provided the method of manufacturing a waterproof structure in a cable insertion section according to the third aspect of the invention, further comprising the steps of: inserting the cable members into a cable insertion opening of the holder body having the cable insertion opening smaller than the plug before the step of inserting the cable members into the sealing body; and detachably engaging the holder body with the cable insertion section while the plug is fittingly squeezed into the cable insertion section.
According to a fifth aspect of the invention, there is provided the method of manufacturing the waterproof structure in the cable insertion section according to any one of the third and fourth aspects of the invention, wherein the cable members are a plurality of electric wires; elastically deformable soft elastic members are respectively provided on edges of openings for leading a cable, which are opposed to each other and is situated on either side of two split dies with reference to a longitudinal direction of the electric wires; and molding material is poured into a cavity while the electric wires are put together in a bundle and sandwiched by elastic deformation of the elastic members of the split dies to mold the plug.
According to a sixth aspect of the invention, there is provided A waterproof mold die for molding a waterproof mold having a large-diameter flange section to be attached to a wiring member having lead wires therein and a small-diameter seal section, the waterproof mold die comprising: a die main body having an upper die and a lower die, the dies constituting a molding surface for the flange section of the waterproof mold; and a cylindrical die having single-piece structure, at least a part of the cylindrical die supported by the upper and lower dies of the die main body, wherein a molding surface for the seal section of the waterproof mold is provided in the cylindrical die.
By means of the foregoing structure, when fused insulation material is poured into the molding surface constituted by the die main body and the cylindrical die, there is formed the waterproof mold having the flange section matching the molding surface defined between the upper and lower dies of the die main body and the seal section having the shape matching the molding surface of the cylindrical die, thereby preventing formation of burrs in an outer peripheral surface of the seal section.
According to a seventh aspect of the invention, there is provided the waterproof mold die according to the sixth aspect of the invention, wherein an insertion section for the wiring member is provided in a junction between the upper and lower dies constituting the die main body; and an elastic sealing material is provided in the insertion section.
By means of the structure set forth, while the wiring member remains inserted into the insertion section, fused insulation material is poured into the molding surface constituted by the die main body and the cylindrical die. As a result, the waterproof mold is formed while the waterproof mold is integrally attached to the outer peripheral surface of the wiring member.
According to a eighth aspect of the invention, there is provided the waterproof mold die according to any one of the seventh and eighth aspects of the invention, wherein one end of the cylindrical die is exposed to the outside of the die main body; a retainer die formed of split dies for retaining the wiring member is provided in the exposed portion of the cylindrical die; a surface tapered to a tip is formed on an outer peripheral section of the retainer die; and a mount hole having another tapered surface, which surface becomes wider toward the outside and matches the tapered surface of the retainer die, is formed in the cylindrical die.
By means of the foregoing structure, while the wiring member remains inserted in the insertion section, fused insulation material is poured into the molding surface constituted by the die main body and the cylindrical die. As a result, the waterproof mold is formed while the waterproof mold is integrally attached to the outer peripheral surface of the wiring material. Subsequently, the retainer die is pulled from the mount hole of the cylindrical die, and the split dies are opened, thereby facilitating a task for removing the cylindrical die from the waterproof mold while the upper and lower dies of the die main body remain in an opened state.